Stiffening member for shoes and the like



Oct. 8 1940. M. c m K 7 54; 2,217,171

STIFFENING MEMBER FOR SHOES AND THE: LIKE Filed Sept 8, 1938 Z a E -IIIIIIIIIIIIIIIIIIIIIIIIII.. ,229

Miles C. Kwz'mz'qk Quenzzzz L. Quin/114212 By 6m ATTORN} lNVENTORJ Patented Oct. 8, 1940 gnaw PATENT OFFICE 2,2l'i,l7i I STIFFENING mivrep a roa 'snons AND THE Miles 0. Kumnick, Kearny, and Quentin L. Quinlivan, Arlington, N. 3., assignors to The Celastic Corporation, Wilmington, DeL, a corporation of Delaware Application September 3, 1938, Serial No. 228,924

6 Claims.

This invention relates to heat-softening stiffening members for shoes, and the like, and, more particularly, to those members ordinarily known as box toes and counters made from a 5 homogeneous plastic composition as distinguished from the more common type made from a fabric impregnated with a thermoplastic substance.

In ordinary shoe making practice, stiffening members are incorporated into the construction while in a soft and'pliable condition which permits of their being pulled into shape over the last. These members fall into two classeswith respect to the method of softening them, the solvent, softening class, which are soaked in or 15 saturated with a solvent. which softens them,

and the heat softening class which are made pliable by heating, usually in a steamer, toabout 80-100 C. This latter is a simpler and preferable technique. 20 ()f the rigid heat softening type of shoe stiffener, most'of thosein commercial use comprise a fabric impregnated with a thermoplastic substance. Solid sheeting of thermoplastic material has not been used heretofore as a heat sof- 2 tening stiffener because it has been impossible to meet, in a single material, the essential requirements that the sheeting become adequately softened for fabrication at 80-100" 0. and that it resist distortion by heat at the temperatures of 80 service. In so far as solid thermoplastic sheeting, e. g., a pyroxylin plastic, has been used for box toes, and thelike, it has been softened by solvent rather than by heat.

The present invention relates to stifieners 0f 35 this solid type which are capable of, being adequately softened by steamer temperatures while adapted to resist distortion at temperatures of service. p

The characteristics which should he possessed 40 by such stiffening members, particularly the box toes used in the construction of dress shoes, have been recognized for many years by the trade but the materials heretofore proposed for use for this purpose have-fallen short of presenting complete 45 combinations of all of the essential features from both the standpoint of fabrication and service.

A stiffening member should be resilient and strong so that if distorted or dented by pressure, it. will resume its original shape upon release of 50 the pressure and not be weakened thereby. Such stiffening members also should not be subject to deterioration or distortion with age nor be damaged by complete immersion in water. From the standpoint of fabricating technique, the mate- W rial for the stiffenershould be of a form and character which will not introduce undue expense and operating difliculties in the construction of the shoe. Its heat softening characteristics must be such that it softens adequately in the ordinary steamer and retains its softness 5 long enough to be formed over the last.

.It is further desirable that, with a minimum of auxiliary treatment to that end, the shoe stiffener should be capable of ceme'nting itself, or of being cemented to adjacent layers in the construction of the shoe so that the latter will have a maximum stability and derive from its adhesion to the box toe a degree of'protection against wrinkling and creasing of one layer over the other. Still further, it is desirable in many cases that a stiffener be of light color so as to impart no undesirable dark undertone to light colored translucent fabrics with which it is usedin fancy shoes.

An object of the present invention is to provide a non-reinforced heat softening material for stiffening elements in shoes, and the like, which shall present a maximum number of the desirable characteristics outlined above and shall be free from the defects exhibited by materials heretofore proposed for this purpose. A further object is to provide such material for stiffening elements of shoes which shall be easily and economically incorporated into the structure of the shoe, shall have strength and resilience to resist distortion and to regain its original shape if distorted, which shall not'be subject to warpage or other deterioration with age and service of the shoe, which shall lend itself readily to adhesion with adjacent layers in the construction of the shoe and which shall be capable of being formed and incorporated into the structure of the shoe so as not to be objectionably visible from the outside of the latter. A still further object is to provide a stiffening material which shall have the 40 advantage of sightliness and thus be adapted to serve'as an externally visible member in the construction of the shoe. Other objects of the invention will be apparent from the description given hereinafter.

The above objects are accomplished according to the present invention by making stiffening members for shoes of a plastic composition comprising ethyl cellulose and a plasticizer in anfi amount ranging from 17-67 parts, by weight, per parts of ethyl cellulose.

It has been discovered that ethyl cellulose suitv ably plasticized within the range given above provides a heat softening plastic which fulfills satisfactorily the'vitalicharacteristics of an ac- 66 may include up to by weight of the total ceptable shoe stiffener of the type herein considered. More specifically, in addition to having the other properties requisite in a plastic for use as a shoe stifiener, suitably plasticized ethyl cellulose gives a stiffening member for use in shoes that is readily softened in the conventional steamer and which is so resilient and strong at temperatures of service in the shoe that it not only imparts the required support to the leather or fabric used in the shoe but, if distorted or dented'by pressure, it will resume its original shape upon release of the'pressure and not be weakened thereby. These ethyl cellulose compositions are adaptedto be worked up into beveled box toe blanks and similar shoe stifiener blanks by processes of thermoplastic molding and particularly by injection moldin It has further been discovered that, by, employ- .ing as the plasticizer for the ethyl cellulose a mixture of a non-exuding plasticizer and an exuding plasticizer, e a amounting to at least 10% of the co bined weightof ethyl cellulose and plasticizers, a composition results which gives a stifiening member that is adhesive at the temperature of lasting. Further, it has been found that the compositions of the present invention composition, of a compatible extender although it is preferred not to employ a compatible extender in excess of 25% of the total weight of the composition.

In Examples I to XI given hereinafter are illustrated specific embodiments of the invention wherein the ethyl cellulose is plasticized with nonexuding plasticizers alone. The non-exuding plasticizers are defined, for the sake of definiteness,= as those plasticizers for ethyl cellulose which are compatible therewith in proportions up'to at least 67 parts per 100 parts of ethyl cellulose without being subject to exudation from the resulting plastic when it is heated to temperatures up to 200 C.

These plasticizers serve primarily to enhance the resilience and strength of-th material and include the following:

Butoxy ethyl stearate Butyl stearate Camphor Castor oil Diamyl adipate Diamyl phthalate Dibutyl phthalate Dibutyl sebacate implienyln esiiill Dibutyl tartrate Diethyl phthalate Dimethoxyethyl phthalate Diphenyl mono-oxenyl phosphate Diphenyl phthalate Dicresoxy diethyl ether r Para-coumarone para-indene resins of liquid type, e

such as those sold under the name Cumar Tributylphosphate Tricresyl phosphate Trl-o-xenyl phosphate Those skilled in the art will understand that by the term ethyl cellulose as used herein, is

meant the high substituted, organic solvent soluble type generallyadapted for use in the plastics field as distinguished from the low substituted type of diiiicult solubility in organic solventsfif soluble at all, andprimarily adapted for uses outside of the plastics field.

In Example 1 given hereinafter reference is made'to the accompanying drawing wherein:

Fig. 1 is a planlview of a box toe blankof con-' ventional form;

Fig. 2 is a section on the line 22 of Fig. 1; Fig. 3 is a section similar to Fig. 2 of a blank of different shape; and

Fig. 4 is a plan view of a blank of still another shape.

The following examples, wherein all parts are given by weight unless other'wiseindicated, illustrate specific embodiments of the invention:

Example I.A homogeneous sheeting composition of 100 parts of ethyl cellulose and 33 parts dicated in Figs. 1 and 2. The bevel ll ordinarily provided by sk-iving is thus provided by molding.

The blank thus made is heated to a temperature of -100 C. on a-steamer and isthereby madelimp, pliable, and capable of being considerably stretched without being torn. While in this limp condition, which is retained for a period of at least 15 seconds, the blank is inserted in the usual manner between a lining and a leather upper and pulled to shape over the toe of a last.

thickness, has sufficient rigidity to resist ordinary distorting forces and, if distorted by heavy pressure or a sharp blow, such as that of a hammer, it will return to its original shape and be neither cracked nor weakened by such treatment. Further, it is not subject to distortion through prolonged severe service wherein it is subject continually to temperatures of the order of 35-45 C. and to high humidity or actual contact with moisture.

In the furtherexamples the method of preparation and. the manner of use may be as in Example I. It will be'evident to those skilled in the art that the-shaped blank with its bevel or scarf, or with other variations from flat sheet form such as general non-uniformity of thickness for the purpose of locally enhancing strength or rigidity as in the shape illustrated in Fig. 3, may be molded not only by compression molding of a continuous preliminary blank cut from sheet or slab material but also by compression molding of the same composition in the discontinuous form fioult, l '1 not altogether ir'npossible.v to impart the Example II Parts I Ethyl cellulose 100 Mixture of phthalic acid esters of alcohols of 6, '7, and 8 carbon atoms 54 I Example III Ethyl cellulose 100 Tricresyl phosphate 54 Example IV Ethyl cellulose 100 Triphenyl phosphate; 33

Example V Ethyl cellulose 100 Tricresyl phos matg 33 Example VI Ethyl cellulose; 100 Mixture of phthalic acid esters of alcohols of 6, '7, and 8 carbon atoms 43 Example VII Ethyl cellulose 100-- Diamyl phthalate 43 Example VIII Ethyl cellulose 100 Octadecanediol diacetate 28 Mixture of phthalic acid esters of alcohols of 6, 7, and 8 carbon atoms 14 Example IX Ethyl cellulose 100 Mixture of phthalic acid esters of alcohols of 6, 7, and 8 carbon atoms 17.5

Example X Ethyl cellulose 100 Mixture of phthalic acid esters of alcohols o 6, 7, and 8 carbon atoms Example XI Ethyl cellulose Q 10o Tributyl phosphate 33 Compositions of the type' illustrated by Examples I to X! do not possess adhesive characteristics when softened by dry heat or by steam. It has been found that the replacement of part or all of the non-exuding plasticizer in compositions of this type by a plasticizer of exuding character confers upon the composition a character of adhesiveness when hot, so that adjacent fabric in the structure of the shoe may therebybe caused to adhere firmly to the stiffening member.

Plasticizers designated as exuding, for the purpose of the present specification, are characterized by being compatible-with ethyl cellulose in that in proportions up to about 50 parts per 100 parts of ethyl cellulose they do not exude more than slightly, at ordinary temperatures, from a plastic of ethyl cellulose with which they have.

been homogeneously incorporated, but are driven to the surface of the plastic upon the application of heat at temperatures above the useful softening temperature of the plastic.

Upon heating a blank containing such a plasticizer in suitable proportions to such a temperature that it becomes adequately softened for use, e. g., to a temperature of from to C., a liquid comes to the surface of the material, and

' if the blank, while in this condition, be inserted in the shoe structure and pulled over the toe of a last, the ordinary pressure applied incidental to thisoperation causes the formation of a bond between the fabric and the ethyl cellulose stiffener. The minimum proportion of exuding plasticizer which imparts a useful adhesiveness to the composition is ten percent of the combined weight of the ethyl cellulose and plasticizer used.

Among the exuding plasticizers particularly ad pted for use in the present invention are s. xric acid and .a mixture composed chiefly of primary, straight chain saturated aliphatic alcohols of 16, 1'7, and, predominantly, 18 carbon atoms derived from hydrogenated cocoanut oil. This latter mixture is a commercial product susceptible to some fluctuation in the proportions of its components; it will be referred to hereinafter as eighteen-carbon alcohol.

Examples of compositions containing exuding plasticizer in proportions sufficient to confer usefuladhesive properties are given in Examples XII to XX:

Example XIII Ethyl cellulose '100 Mixture of phthalic acid esters of alcohols of 6, 7, and 8 carbon atoms"-- Eighteen-carbon alcohol 23 Example XIV Ethyl cellulose 100 'Mixture of phthalic acid esters of alcohols of 6, '7, and 8 carbon atoms 1 14 Eighteen-carbon alcohol 29 Example XV Ethyl cellulose 100 Tricresyl phosphate 23 Eighteen-carbon .alcohol 31 Example XVI Ethyl cellulose 100 Mixture of phthalic acid esters of alcohols of 6, 'l, and 8 carbon atoms 25 stearic acid 23 I' Example XVII I Ethyl cellulose 100 Mixture of phthalic acid esters of alcohols of 6, 7, and 8 carbon atoms 50 Eighteen-carbon alcohol 15 Example XVIII Ethyl cellulose 100 Mixture of phthalic acid esters of alcohols of 6, 7, and 8 carbon atoms Stearic acid 15 Example XIX Ethyl cellulose 10o Mixture of phthalic acid esters of alcohols of 6, '7, and 8 carbon atoms, 5 Eighteen-carbon alcohol 15v Example XX Ethyl cellulose 100 Mixture of phthalic acid esters of alcohols of 6, 7, and 8 carbon atoms Stearic acid 15 If desired, the non-exudingiplasticizer may be omitted altogether and one or a mixture of the exuding plasticizers may be used as the plasticizer, as indicated in Examples m to xxm.

This, however, is not preferred, as the resulting compositions do not have quite the resilience and strength of those containing non-exuding plasticizer:

Example XXI .Parts Ethyl cellulose 100 Eighteen-carbon alcohol 40 I Example XXII Ethyl cellulose -1 100 Stearic acid 40 Example XXIII Ethylcellulose 10o Eighteen-carbon alcohol 20 Stearic ac '20 The mixtures'of ethyl cellulose and plasticizer may be modified by the addition of compatibleextenders, primarily for the purpose of reducing the materials cost of the mixtures. The term extenders is used herein to characterize substances which may be homogeneously incorporated with ethyl cellulose and the plasticizers already mentioned, but which possess only very weak plasticizing power, if any, and which, in the proportions used, do not exude more than slightly from the plastic.

Suitable extenders include the following: Light-colored petroleum asphalt, such as that sold under the name Albinalt Beeswax 1; Candelilla wax Camauba wax Cetyl alcohol Chlorinated diphenyl, such as that sold under the name Aroclor Hydrogenated castor oil, such as that sold under the name Opalwax Japan wax Mineral rubber (Gilsonite) Montanwax Oleic acid Para-coumarone para-indene resins, such as those sold under the name Cumar, of both solid and liquid types Rosin Spermaceti Stearin pitch Tallow In mixtures containing extenders the ratio of ethyl cellulose to plasticizer is maintained in the rangealready set forth, and the percentage of extender in the mixture of ethyl cellulose, plasticizer, and extender, is not excess of 50 percent, while about 25 percent is: preferred as the limit. 3

Compositions containing such extenders are illustrated by Examples XXIV to Example XXIV Lightcolored'petroleum wax 25- Example XXVI Parts Ethyl cellulose 63 Mixture of phthalic acid esters of alcohols of 6, 7, and 8 carbon atoms 21 Carnauba wax 1 16 '(33) Example XXVII Ethyl cellulose 70 (100) Mixture of phthalic acid esters of alcohols 01 6,, 7, and 8 carbon atoms 15 (215) Hydrogenated castor oil 15 Example xxvm Ethyl cellulose r 55 (100) Mixture-of phthalic acid esters of alcohols of 6, 7, and 8 carbon atoms 15 Chlorinated diphenyl 15 (27.5) Rosin 15 Example XXIX Ethyl cellulose 70 '(100) Mixture of phthalic acid esters of alcohols of 6, 7, and 8 carbon atoms 15 '(215) Chlorinated-diphenyl 15 I Example XXX Ethyl cellulose "55 (100) Mixture of phthalic acid esters of alcohols of 6, 7 and 8 carbon atoms- 35 (64) Montan wax". 10

It will be understood that the above examples are merely illustrative and that the invention broadly comprises employing properly plasticized ethyl cellulose in nonrelnforced stiffening members for shoes. While numerous specific examples of ethyl cellulose compositions have been given, as well a's the range of proportions of plasticizers, the optimum composition using any particular plasticizer, or combination of plasticlzers, for a desired purpose will involve some preliminary testing as those skilled in the art will appreciate.

The ethyl cellulose compositions of the present invention may be fabricated into blanks for box toes of ornamental character. Such stifieners are adapted to be used without the usual outer covering of leather or fabric,and thus to be visible as an ornamental element of the shoe. Those I stifiener's of translucent or transparent character shoe construction useful in obtaining novel effects in womens fancy shoes. 7

Many of the compositions set forth in the examples are approximately colorless and transparent and can be used'unchanged for these bare or partially covered box toes. Or they may be colored to desired hues and made translucent or opaque if preferred. Preferably, box toe elements of this type will be made from compositions; free from exuding plasticizers and free from extenders.

The present invention is not only applicable to stiifening members for box toes but is also applicable to stiffening members used as counters in shoes. The materials of the present invention,

supplied in the form of sheeting or blanks, can be shaped into counters by the technique 'of heat softening followed by swaging in a cold mold or molding powders of plasticized ethyl cellulose may be molded directly into shaped counters.

Not only are the compositions of the present invention suitable for shoe stiffeners but they may also be used where similar requirement of toughness, resilience, water-proofness, and the like are required, particularly in articles of arched shape and including protective equipment for sports and games, arch supports, artificial limbs, and the'like. I

An advantage of the present invention is that it provides shoe stiffeners of marked superiority 1 over materials heretofore available in the preferred heat softening class and that box toes of the herein described ethyl cellulose composition, with no support or reinforcement as woven fabric, felt, wire netting, loose fiber, and the like, are superior to heat softening stiffeners heretofore proposed even when so supportedor reinforced. A further advantage of the present invention lies in the superior toughness and resilience of the stiffening members, particularly along the beveled or skived edges. These stiffening members have no inherent tendency to lose their shape, are not softened to the point of distortion by ordinary temperatures of service, and are unaffected by water.

A particular advantage of the shoe stiffeners of the type employing an exuding plasticizer is that their adhesiveness is not accompanied by staining of the external material of the shoe. The present-compositions may readily be made colorless or light colored and hence free from the tendency which dark colored stiffeners have,

of imparting an undesirable graying to the delicate tints of fine fabric shoes.

When the blanks of this invention are molded from molding powder, by either injection or compression molding, there is no appreciable waste or loss of material and the invention thus offers this distinct advantage in economy over the ordinary practice of cutting blanks from sheet material and beveling them by skiving which gives rise to a loss of as much as 20-30% of the sheet material in the form of skeleton scrap and skivi'ngs. Also, because of the thermoplastic character of the present compositions, and the absence of reinforcing fabric and the like, any scrap that may be produced in the shaping or use of the blanks of this invention (such as the sprue made in injection molding) is immediately and completely reusable.

Blanks of the present material have the highly essential characteristic of becoming verylimp and flexible at a temperature of about 80-100 C.,

which is below the temperature that will cause injury to leather and, further, have the advantage of retaining this limpness, after removal of the blanks from the source of. heat, for a period entirely adequate for the shaping of the blank over the last. Despite the limpness and pliability of the blanks, they are tenacious in character and can be pulled over the last without being torn. Also, as the stiffening member, after steaming, cools down toward room temperature, it still retains adequate toughness so that nails may be driven through it without causing it to crack.

As many apparently widely different embodiments of this invention may be made without departing from the spirit andscope thereof, it is to be understood that the invention is not limited .heated to a temperature of 80-100 C., andcomprising 100 parts of ethyl cellulose and 17-67 parts of a non-exuding plasticizer.

3; A molded, non-reenforced shoe stilfener blankadapted to be softened for lasting by being heated to a temperature of 80-100 C., and comprising 100 parts of ethyl cellulose and 17-67 parts of a mixture of non-exuding and exuding plasticizers, the exuding plasticizer being present in an amount at least equal to 10% of the combined weight of the ethyl cellulose and plasti- ClZeIS.

4. A molded, non-reenforced shoe stiffener blank adapted to be softened for lasting by being heated to a temperature of 80-100 C., and comprising 100 parts of ethyl cellulose, 17-67 parts of plasticizer, and a compatible extender, said extender being present in an amount not exceeding 50% of the total weight of the composition.

5. A molded, non-reenforced shoe stiffener blank adapted to be softened for lasting by being heated to a temperature of 80-100 C., and comprising 100 parts of ethyl cellulose, 17-67 .parts of a non-exuding plasticizer, and a compatible extender, said extender being present in an amount not exceeding 50% of the total weightof the composition.

6. A molded, non-reenforced shoe stiffener blank adapted to be softened for lasting by being heated to'a temperature of 80-l00 C., and comprising 100 parts of ethyl cellulose, 17-67 parts of a mixture of non-exuding and exuding plasticizers, the exuding plasticizer being present in an amount at least equal to 10% of the combined weight of the ethyl cellulose and plasticizers, and a compatible extender, said extender being present in an amount not exceeding 25% of the total weight of the composition.

MILES C. KUMN ICK. QUENTIN L. QUINLIVAN. 

